The response of vegetated dunes to wave attack

• Published in: Coastal engineering (Amsterdam) 2019-10, Vol.152, p.103506, Article 103506
• Main Authors: Bryant, Duncan B., Anderson Bryant, Mary, Sharp, Jeremy A., Bell, Gary L., Moore, Christine
• Format: Article
• Language: English
• Subjects: Dunes; Erosion; Overwash; Sediment transport; Vegetation; Wave overtopping
• ISSN: 0378-3839; 1872-7379
• DOI: 10.1016/j.coastaleng.2019.103506

For many coastal communities, dunes serve as the primary defense against tropical and extratropical events. Vegetation is believed to increase the stability of dunes during wave attack, but limited data is available. A physical model study was performed to evaluate changes in the dune stability with and without biomass, both above and belowground. The above and belowground biomass was modeled using wooden dowels and coir fibers, respectively. For both the collision and overwash storm impact regimes, the results of this study clearly demonstrate that the inclusion of biomass in the model dune reduces the erosion and overwash. The combination of both above and belowground biomass was the most effective at reducing erosion followed by belowground biomass, with aboveground biomass providing the smallest benefit regardless of the wave condition and water level. Additionally, the overwash of sediment and water was decreased with the inclusion of biomass, following the same trends as the erosion. As the dune eroded, the storm impact regime transitioned from collision to overwash. The inclusion of biomass delays this transition in storm impact regime, providing greater protection to coastal communities. This study highlights the need to consider dune vegetation for dune construction and coastal planning. •Physical model study to evaluate dune stability with and without biomass.•A novel approach to modeling belowground biomass in dunes.•Vegetation biomass is demonstrated to provide dune stability during wave attack.•Biomass delays the transition in the storm impact regime.